Laser processing device, three-dimensional shaping device, and laser processing method

ABSTRACT

A laser processing device includes plural laser sources and a focusing section that focuses respective light beams of the plural laser sources to form plural focus points on a workpiece, and that focuses such that respective portions of at least some of the plural focus points are overlapping.

TECHNICAL FIELD

Technology of the present disclosure relates to a laser processingdevice, a three-dimensional shaping device, and a laser processingmethod.

BACKGROUND ART

With regard to laser processing devices, in situations where variousinvestigations have been made to improve processing characteristics, andespecially to raise energy efficiency, investigations have also beenmade into laser processing devices employing plural beam spots or pluralwavelengths. Non-Patent Document 1, for example, describes a knownexample of such an investigation. The laser processing device describedin Non-Patent Document 1 attempts to control input heat distribution andimprove processing characteristics by spatially splitting a beam of alaser source. Namely, plural optical systems (focusing lenses) havingdifferent focal point positions are employed for a single beam tocontrol input heat, and processing such as cutting or welding isperformed. Note that “input heat” refers to the amount of heat appliedfrom the exterior to the processing point and the vicinity thereofduring processing.

Further, Non-Patent Document 2 describes another example of a laserprocessing device in which improving energy efficiency was investigated.The laser processing device described in Non-Patent Document 2 employslight sources of plural wavelengths, and emits light from asemiconductor laser and light from a YAG laser onto the same focus pointusing a single multimode fiber. The laser processing device described byNon-Patent Document 2 utilizes the fact that a wavelength of light froma single semiconductor laser is absorbed by Al (aluminum) highlyefficiently.

CITATION LIST Non Patent Literature

-   NPL 1: J. Xie, Welding Journal 223-S, 2002-   NPL 2: K. Miura et al., JLMN-Journal of Laser Micro/Nanoengineering,    Vol. 6(3), 225-230, 2011

SUMMARY OF INVENTION Technical Problem

In laser processing devices that employ plural beam spots or pluralwavelengths, it is conceivable that employment of synergistic effectsbetween the plural beam spots or between the plural wavelengths will beimportant technology for improving processing characteristics.

Regarding this point, the mere presence of plural beam spots is notexpected to give rise to synergistic effects between plural beam spotsin optical systems, such as the laser processing device described byNon-Patent Document 1, which is implemented by splitting asingle-wavelength laser beam. Namely, in the laser processing devicedescribed by Non-Patent Document 1, for example, phenomena such asheterodyne effects caused by interference do not occur since two beamshaving the same wavelength are merely overlapped at the focus point.Accordingly, absorption characteristics are not expected to be improvedby beam superimposition.

Further, although laser light from different laser sources is employedin the laser processing device described by Non-Patent Document 2,interactions such as heterodyne effects do not occur after deliverythrough a multimode fiber. Further, controlling input heat profiles atthe focus point is difficult in cases in which plural laser beamsobtained from the same emitting end are focused by the same lens. Theprocessing characteristics of a laser processing device are generallydetermined by the wavelength of the laser light (namely, independentabsorption characteristics) and the absorption characteristics of theworkpiece, and the accompanying input heat distribution is mainlydefined by an emission profile.

Technology disclosed herein provides a laser processing device, athree-dimensional shaping device, and a laser processing method thatenable a profile of heat input to a workpiece to be controlled with highprecision, and that achieve processing with high energy efficiency.

Solution to Problem

A laser processing device according to a first aspect includes plurallaser sources and a focusing section that focuses respective light beamsof the plural laser sources to form plural focus points on a workpiece,such that respective portions of at least some of the plural focuspoints are overlapping.

A laser processing device according to a second aspect is the laserprocessing device according to the first aspect, wherein respectivelights of the plural laser sources have identical wavelengths, sizes ofthe plural focus points differ from one another, and one of the focuspoints internally encompasses another of the focus points.

A laser processing device according to a third aspect is the laserprocessing device according to the second aspect, wherein the pluralrespective laser sources have been split from a single laser source.

A laser processing device according to a fourth aspect is the laserprocessing device according to any one of the first aspect to the thirdaspect, further including a controller that, when performing laserprocessing, after melting the workpiece at a region where two of thefocus points are overlapped, controls an input heat profile at a regionwhere the two focus points do not overlap.

A laser processing device according to a fifth aspect is the laserprocessing device according to the first aspect, wherein respectivelights of the plural laser sources have different wavelengths, sizes ofthe plural focus points differ from one another, and one of the focuspoints internally encompasses another of the focus points.

A laser processing device according to a sixth aspect is the laserprocessing device according to the first aspect or the fifth aspect,wherein the plural laser sources is two laser sources having mutuallydifferent wavelengths, and the laser processing device further includesa controller that, when performing laser processing, after melting theworkpiece at a region where two of the focus points are overlapped,controls an input heat profile at a region where the two focus points donot overlap.

A laser processing device according to a seventh aspect is the laserprocessing device according to any one of the first aspect of the sixthaspect, wherein the focusing section includes an optical system thatfocuses each of the respective light beams.

A three-dimensional shaping device according to an eighth aspectincludes a laminating section including a material supply section thatsupplies a material for performing lamination to form a laminatedobject, and the laser processing device according to any one of thefirst aspect to the seventh aspect, wherein the laminating sectionperforms lamination by supplying the material onto the laminated objectfrom the material supply section while moving the laminated objectrelative to the material supply section and the light beams, and byemitting the light beams onto the supplied material.

A laser processing method according to a ninth aspect is performed by alaser processing device that includes a plural laser sources and afocusing section that focuses respective light beams of the plural lasersources to form plural focus points on a workpiece, the laser processingmethod includes focusing using the focusing section such that respectiveportions of at least some of the plural focus points are overlapping.

A laser processing method according to a tenth aspect is the laserprocessing method according to the ninth aspect, wherein the plurallaser sources is two laser sources having mutually differentwavelengths, and the laser processing method further includes meltingthe workpiece in a region where two of the focus points are overlapped,and controlling an input heat profile at a region where the two focuspoints are not overlapping.

Advantageous Effects of Invention

One exemplary embodiment of technology disclosed herein has anadvantageous effect of enabling a laser processing device, athree-dimensional shaping device, and a laser processing method to beprovided that enable a profile of heat input to a workpiece to becontrolled with higher precision, and that achieve processing withhigher energy efficiency.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a diagram illustrating an example of a configuration of alaser processing device according to a first exemplary embodiment, and abeam spot of the laser processing device.

FIG. 1B is an enlarged view of a superimposition spot.

FIG. 1C is an enlarged view of a superimposition spot.

FIG. 2A is a graph for explaining principles of a laser processingdevice according to an exemplary embodiment, and is a graph illustratingan example of a mode of time-wise changes in a carrier component and anenvelope component.

FIG. 2B is a graph for explaining principles of a laser processingdevice according to an exemplary embodiment, and is a graph illustratingan example of intensity modulation components for processingfrequencies.

FIG. 2C is a graph for explaining principles of a laser processingdevice according to an exemplary embodiment, and is a graph illustratingan example of a mode of change to modulation intensity with respect tochanges in power ratio.

FIG. 3 is a graph illustrating an example of a configuration of a laserprocessing device according to a second exemplary embodiment.

FIG. 4 is a graph illustrating an example of a configuration of a laserprocessing device according to a third exemplary embodiment.

FIG. 5A is a diagram illustrating an example of a configuration of alaser processing device according to a fourth exemplary embodiment.

FIG. 5B is a diagram illustrating a modified example of a configurationof a laser processing device according to the fourth exemplaryembodiment.

FIG. 6A is a diagram illustrating an example of a configuration of a 3Dprinter according to a fifth exemplary embodiment.

FIG. 6B is a diagram illustrating an example of a mode of a metalpowder/conveyance gas channel with a shielding gas channel in cases inwhich a nozzle is viewed from a leading end.

FIG. 7 is a block diagram illustrating an example of a hardwareconfiguration of an electrical system of a laser processing deviceaccording to an exemplary embodiment.

FIG. 8 is a conceptual diagram illustrating an example of a mode inwhich a program is installed to a laser processing device from a storagemedium stored with the program.

DESCRIPTION OF EMBODIMENTS

Detailed explanation follows regarding exemplary embodiments oftechnology disclosed herein, with reference to the drawings.

First Exemplary Embodiment

Explanation follows regarding a laser processing device 10 according toan exemplary embodiment, with reference to FIG. 1A, FIG. 1B, FIG. 1C,FIG. 2A, FIG. 2B, and FIG. 2C. As illustrated as an example in FIG. 1A,the laser processing device 10 includes an optical system 12, a lasersource 14, and a laser source 16. Note that, although light sources ofplural wavelengths can be employed in technology disclosed herein, inthe present exemplary embodiment explanation is given using an examplein which two wavelengths are employed.

The laser source 14 and the laser source 16 are heat sources that supplyheat during processing. A solid-state laser, a fiber laser, or the likemay be employed therefor in the present exemplary embodiment, but thereare no particular limitations thereto. In the present exemplaryembodiment, the wavelength of the laser source 14 is λ1, the wavelengthof the laser source 16 is λ2, and both of these wavelengths aredifferent (λ1≠λ2). For example, wavelengths within a 1.00 μm band may beset as the wavelengths λ1 and λ2. Further, although the laser sources 14and 16 are typically continuous wave (CW) types, pulsed light may beemployed. Further, the polarization state of the laser lights of thelaser sources 14 and 16 according to the present exemplary embodiment isone of linear polarization. However, there is no limitation thereto, andin consideration of processing efficiency and the like, circularlypolarized light may be employed, or one laser source may be a source ofcircularly polarized light and the other laser source may be a source oflinearly polarized light.

The optical system 12 is a section where light emitted from the lasersource 14 and light emitted from the laser source 16 are eachindependently focused. As illustrated as an example in FIG. 1A, theoptical system 12 is configured including: a lens 18 and a lens 20 thatfocus a light beam L1 emitted from the laser source 14; and a lens 22and a lens 24 that focus a light beam L2 emitted from the laser source16.

As illustrated as an example in FIG. 1A, the light beam L1 emitted fromthe laser source 14 and the light beam L2 emitted from the laser source16 are each focused on the surface of a workpiece W after having beenfocused by the optical system 12, thereby forming a spot S, which is aspot where a laser beam spot (focus point) of each laser beam issuperimposed on a processing point P (a region where processing iscarried out on the workpiece W). Note that the formation position of thesuperimposition spot S on the workpiece W is not necessarily limited tothe surface of the workpiece W, and the superimposition spot S may beformed inside the workpiece W in accordance with the material and thelike of the workpiece W.

FIG. 1B illustrates an enlarged view of a superimposition spot S. Asillustrated as an example in FIG. 1B, the superimposition spot Saccording to the present exemplary embodiment is formed by superimposingthe spot S1 from the laser source 14 (the light beam L1) with the spotS2 from the laser source 16 (the light beam L2). In the superimpositionspot S, the energy density in the region where the spot S1 issuperimposed with the spot S2 is higher than the energy density ofregions where the spot S1 is not superimposed with the spot S2. In thepresent exemplary embodiment, although the superimposition spot S isformed such that the spot S2 encompasses the spot S1 as illustrated asan example in FIG. 1B, the superimposition state of the spot S1 with thespot S2 is not limited thereto. Further, in the present exemplaryembodiment, although explanation is given using an example in which theshapes of the spots S, S1, and S2 are circular shapes, there is nolimitation thereto. In accordance with the details of the processing andthe like, an appropriate shape such as a straight line shape or arectangular shape may be selected, and the shapes of the spots maydiffer from one another. Note that the superimposition state of the spotS1 with the spot S2 is described in detail later.

As illustrated as an example in FIG. 1C, in an superimposition spot S, aregion in which a spot S1 and a spot S2 are superimposed (the region ofspot S1 in the example illustrated in FIG. 1C) is referred to as a“superimposition region OA”, and a region in which the spot S1 and thespot S2 are not superimposed is referred to as a “no-superimpositionregion NA” (the region having only spot S2 in the example illustrated inFIG. 1C). Further, a focus diameter (spot size) R1 of the spot S1 and afocus diameter (spot size) R2 of the spot S2 are defined as illustratedas an example in FIG. 1C. The focus diameters according to the presentexemplary embodiment are, for example, R1=50 μm and R2=100 μm.

As illustrated as an example in FIG. 7, the laser processing device 10includes a controller 300. The controller 300 includes a CPU 302 servingas a central processing unit, a primary storage section 304, and asecondary storage section 306. Examples of the primary storage section304 include RAM serving as random access memory. Examples of thesecondary storage section 306 include ROM serving as read-only memory.Note that other examples of the secondary storage section 306 includenon-volatile memory such as electrically erasable programmable read onlymemory (EEPROM) or flash memory.

The secondary storage section 306 stores various programs including aprogram 308, various profiles such as a beam profile and an input heatprofile, various parameters, and the like.

The CPU 302, the primary storage section 304, and the secondary storagesection 306 are connected to one another through a bus line 308.Accordingly, the CPU 302 reads the various programs from the secondarystorage section 306, expands the various programs into the primarystorage section 304, and executes each of the various programs.

In particular, the CPU 302 operates as a controller according totechnology disclosed herein by executing the program 308. Namely, whenperforming laser processing, the CPU 302 controls the input heat profileat a region where there are not two overlapping focus points, afterhaving caused melting of the workpiece in the region where the two focuspoints have been overlapped.

In cutting processing and welding processing of a workpiece such asmetal, it is difficult to effectively use energy from a laser sourcesince the ratio of laser light reflected by the surface of the workpieceis generally high. However, the absorption efficiency of the laser lightcan be raised by initially melting a portion of the surface of theworkpiece using laser light emission.

Thus, in the present exemplary embodiment, the superimposition spot Swhere the two spots S1 and S2 are superimposed is focused on aprocessing point P, so as to first cause slight melting in the highlyfocused (high energy density) superimposition region OA. Thus, one laserbeam is focused, the surface of the workpiece W is melted by the focusedlaser beam, and processing characteristics are improved compared toperforming cutting processing or welding processing with the same laserbeam profile as-is. Further, by configuring the no-superimpositionregion NA, the CPU 302 can independently control suitable beam profilestypical for executing cutting processing and welding processing,enabling processing to be performed with high energy efficiency.

Further, in the present exemplary embodiment, in the superimpositionregion OA, which is a region where the spots of two laser lights havingdifferent wavelengths are superimposed, heterodyne interference occursdue to interference between the two laser lights, and the heterodyneinterference is used in the laser processing.

Namely, in the present exemplary embodiment employing two laser beams,heterodyne interference is caused by superimposing the laser beamshaving the wavelengths λ1 and λ2 (in other words, optical frequencies ofω1 and ω2). This then generates a superimposition beam of a carriercomponent expressed by frequency (ω1+ω2)/2 and an envelope componentexpressed by (ω1−2)/2. By selecting the frequencies ω1 and ω2 inaccordance with the processing conditions, the frequency (ω1+ω2)/2 ofthe carrier component acts like a third wavelength λ3 that influencesthe absorption characteristics of the workpiece W, and the CPU 302controls the processing characteristics using the frequency (ω1−ω2)/2 ofthe envelope component. It is thereby possible to achieve laserprocessing equivalent to having introduced a new wavelength withimproved energy efficiency. Namely, the absorption characteristics ofthe superimposition region OA are determined by the carrier frequencyand the absorption characteristics of the workpiece, and the absorptioncharacteristics in the superimposition region OA can be raised byappropriately selecting the carrier frequency. Further, the carrierfrequency could also be set such that such that the reflection ratio israised at the superimposition region OA, if necessary. In such a case,the combination of the wavelengths λ1 and λ2 can be appropriatelyselected by considering the absorption wavelength characteristics of theworkpiece W.

More detailed explanation follows regarding the heterodyne effectaccording to the present exemplary embodiment, namely, generation of thecarrier component and the envelope component, with reference to FIG. 2.The electric field distributions of the two laser lights havingdifferent wavelengths are expressed by Equation 1 and Equation 2 below.

[Math.1]

E ₁(t)=E ₁·exp{j(ω₁ t+φ ₁)}  Equation 1

[Math.2]

E ₂(t)=E ₂·exp{j(ω₂ t+φ ₂)}  Equation 2

The two laser lights having the electric field distributions expressedby Equation 1 and Equation 2 are combined on the surface of theworkpiece, and the electromagnetic field when interference has occurredis expressed by Equation 3 below, which is obtained by multiplyingEquation 1 by Equation 2. Note that Equation 3 is derived when E₀=E₁=E₂to simplify the logic.

     [Math.3] $\begin{matrix}{{E(t)} = {2{E_{0} \cdot \cos}{\left\{ \frac{{\left( {\omega_{1} - \omega_{2}} \right)t} + \left( {\phi_{1} - \phi_{2}} \right)}{2} \right\} \cdot \exp}\left\{ {j\frac{{\left( {\omega_{1} + \omega_{2}} \right)t} + \left( {\phi_{1} + \phi_{2}} \right)}{2}} \right\}}} & {{Equation}\mspace{14mu} 3}\end{matrix}$

It is apparent from Equation 3 that an electric field distribution fromthe carrier component expressed by frequency ωc=(ω1+ω2)/2, and anelectric field component from the envelope component expressed byfrequency e=(ω1−ω2)/2, are generated. FIG. 2A illustrates the carriercomponent Car and the envelope component Env on a plot having time onthe horizontal axis and electric field E on the vertical axis. When thefrequency (processing frequency) employed in the processing of the laserprocessing device 10 is ωc, from FIG. 2A, the intensity of theprocessing frequency ωc can be described as being rapidly modulated bythe frequency ωe of the envelope component. Namely, in thesuperimposition region OA, the reflection ratio characteristics or theabsorption characteristics for a material are similar to thecharacteristics for the laser light having frequency ωc, and the laserlight having frequency ωc behaves as if intensity modulated by thefrequency ωe.

However, when the heterodyne effect is represented, the opticalintensity |E(t)|² of the envelope component is represented by Equation 4below.

     [Math.4] $\begin{matrix}{\left| {E(t)} \right|^{2} = {{\left( {{E_{1}(t)} + {E_{2}(t)}} \right)\left( {{E_{1}(t)} + {E_{2}(t)}} \right)^{*}} = \mspace{59mu} \left| E_{1} \middle| {}_{2}{+ \left| E_{2} \middle| {}_{2}{{+ 2} \cdot} \middle| \left. E_{1}||E_{2} \right. \middle| {{\cdot \cos}\left\{ {{\left( {\omega_{1} - \omega_{2}} \right)t} + \mspace{554mu} \left( {\phi_{1} - \phi_{2}} \right)} \right\}} \right.} \right.}} & {{Equation}\mspace{14mu} 4}\end{matrix}$

A plot of Equation 4 yields, for example, FIG. 2B. FIG. 2B is a plotobtained from the above, of the intensity modulation component for theprocessing frequency ωc.

FIG. 2C illustrates an amplitude magnitude (modulation intensity orbrightness) of an interference signal generated by laser light from thelaser source 14 and the laser source 16, which are two laser sourceshaving different wavelengths. The power of the laser lights from the twolaser sources are respectively denoted P1 and P2, and the power ratio kis defined as k=P1/P2. FIG. 2C has power ratio k on the horizontal axis,and change in the modulation intensity m is plotted against the powerratio k. In the example illustrated in FIG. 2C, for example, when k=1,namely, in cases in which the power of the laser lights from the twolaser sources are equal, this means that the amplitude 2|E1|·|E2|illustrated in FIG. 2B is in a state of changing between 0 and a maximumvalue.

Here, explanation follows regarding polarization of laser light from thelaser source 14 and the laser source 16 (wave polarization). In thelaser processing device 10, it is necessary to match the planes ofpolarized light (wave polarization) to each other since interferencephenomena between laser light from the laser source 14 and laser lightfrom the laser source 16 is employed. Note that in the present exemplaryembodiment, “match the planes of polarized light to each other” does notonly refer to cases of matching perfectly, but also includes cases ofmatching with a predetermined permissible drop in interference.

The polarization of laser light from the laser source 14 and the lasersource 16 according to the present exemplary embodiment is preferablylinear polarization for both laser lights. It is most efficient toemploy the characteristics of light beams produced by interferencebetween linearly polarized light beams. However, interference betweenlinearly polarized light and circularly polarized light (or randomlypolarized light or unpolarized light), or interference betweencircularly polarized light beams can be employed. Although laser lightsent using an optical fiber can be employed, for interference effects tobe expected, it is preferable to employ laser light that has propagatedthrough a single-mode optical fiber or low-dimension mode laser lightdelivered through an optical fiber capable of high-mode delivery. Notethat “randomly polarized light” is polarized light in which the linearpolarization direction of the light is aperiodically changed.“Unpolarized light” is light for which the linear polarization directionof the light is evenly mixed over a 360° range.

Next, explanation follows regarding the superimposition state of thespot S1 of the laser light from the laser source 14 with the spot S2 ofthe laser light from the laser source 16. As described above, in thepresent exemplary embodiment, at least a portion of the spot S1 and thespot S2 overlap with each other, namely, it is a presupposition that thespot S1 and the spot S2 are superimposed. However, there are variousconceivable forms of this superimposition. In the case of two spots, amode in which one spot is completely encompassed by the other spot, asillustrated as an example in FIG. 1B, is preferable. However, there isno limitation thereto; even modes in which the position of the spot S1is offset from the position illustrated in FIG. 1B and a portion of thespot S1 falls outside of the spot S2 can be employed by, for example,providing a permissible range of lowered interference efficiency.Conversely, interference effects cannot be expected in cases in whichthe spot S1 and the spot S2 exist independently with no overlap at all.

Note that the number of spots is three or more in some cases since threeor more laser sources can be employed in technology disclosed herein.When employing three or more spots, for example, three spots S3, S4, andS5 using three laser sources, a mode in which the spot S3 and the spotS4 are contained within the spot S5 is conceivable as an example.Further, in such cases, modes in which the spot S3 and the spot S4 donot overlap at all, modes in which the spot S3 is contained within thespot S4, and the like are conceivable inside the spot S5. Further, amode in which a portion of at least one out of the spot S3 or the spotS4 falls outside of the spot S5 is also conceivable. Employing three ormore spots enables the CPU 302 to control the input heat profile withhigh precision.

Next, explanation follows regarding an example case in which theprocessing performance of the laser processing device 10 is comparedagainst the processing performance of a laser processing deviceaccording to related technology. The present example case is an examplecase in which a metal sheet is cut by both laser processing devices andthe quality of the processing is compared.

COMPARATIVE EXAMPLE

In the laser processing device according to related technology thatemploys a single laser source, mild steel having a plate thickness of1.5 mm was cut using a laser light of a 900 W laser source constrainedto a spot having a 300 μm focus diameter (diameter). It was found that acut could be made with excellent product quality as a result. A cuffwidth needs to be controlled as a cutting margin (a width needed to blowaway the melted metal), and an optimum width was 300 μm.

Present Exemplary Embodiment

Applying an optical system according to the present exemplary embodimentillustrated as an example in FIG. 1, mild steel having a sheet thicknessof 1.5 mm was cut using a superimposed laser beam of the laser light ofthe laser source 14, which had a power of 300 W, constrained to the spotS1 having a focus diameter of 150 μm, and the laser light of the lasersource 16, which had a power of 300 W, constrained to the spot S2 havinga focus diameter of 300 μm. It was found that cutting of equivalentquality to that of the comparative example was possible as a result.

Namely, it was found that using the laser processing device 10 accordingto the present exemplary embodiment improved energy efficiency byapproximately 33% ((1−300 W×2/900 W)×100).

As described in detail above, the laser processing device and the laserprocessing method according to the present exemplary embodiment achievea laser processing device and a laser processing method having excellentenergy efficiency by superimposing emitted light from plural lasersources having different wavelengths (in other words, opticalfrequencies) as described above at the processing point and forming thesuperimposition spot S as illustrated in FIG. 1B. Further, a laserprocessing device and a laser processing method are achieved in whichthe CPU 302 can control the input heat (energy density) input to theworkpiece by controlling the overlap distribution of the beam. Namely,the CPU 302 controls the beam profile (the shape of the superimpositionspot S) at the focus point of the plural beams (having differentwavelengths and a focus characteristics), and input heat characteristicsand absorption characteristics of the workpiece can be independentlycontrolled by employing interference effects between the laser lightscaused by the superimposition, thus achieving cutting or weldingprocessing having high energy efficiency.

Second Exemplary Embodiment

Explanation follows regarding a laser processing device 30 according toan exemplary embodiment, with reference to FIG. 3. The present exemplaryembodiment is an embodiment in which the optical system of the exemplaryembodiment above has been changed.

As illustrated as an example in FIG. 3, the laser processing device 30includes a laser source 34, a laser source 36, and an optical system 32.The wavelength of the laser source 34 is λ1, and the wavelength of thelaser source 36 is λ2 (≠λ1).

The optical system 32 according to the present exemplary embodiment isconfigured including lenses 38, 40, and 42. The lens 38 focuses a lightbeam L1 from the laser source 34. The lens 40 focuses a light beam L2from the laser source 36. The light beam L1 focused by the lens 38 andthe light beam L2 focused by the lens 40 are each further focused by thelens 42, and a superimposition spot S (see FIG. 1B) are formed at theprocessing point P of the workpiece W as a result.

The laser processing device according to the present exemplaryembodiment enables the optical system to be configured more simply thanin the exemplary embodiment above since the number of lenses is reducedby making some of the lenses common.

Third Exemplary Embodiment

Explanation follows regarding a laser processing device 50 according toan exemplary embodiment, with reference to FIG. 4. The present exemplaryembodiment is an embodiment in which the optical system of the exemplaryembodiment above has been changed.

As illustrated as an example in FIG. 4, the laser processing device 50includes a laser source having a wavelength λ1, a laser source having awavelength λ2 (these are omitted from the drawings), and an opticalsystem 52.

The optical system 52 according to the present exemplary embodiment isconfigured including mirrors 54 and 56, and a lens 58. A light beam L1from the laser source having the wavelength λ1 is reflected atsubstantially a right angle by the mirror 54 and aimed toward the lens58, and is focused at the processing point P of the workpiece W. A lightbeam L2 from the laser source having the wavelength λ2 is reflected atsubstantially a right angle by the minor 56 and aimed toward the lens58, and is focused at the processing point P of the workpiece W. Thesuperimposition spot S is formed at the processing point as a result.

The laser processing device according to the present exemplaryembodiment enables the optical system to be configured more simply thanin the exemplary embodiment above since the number of lenses is furtherreduced by applying mirrors to the optical system.

Fourth Exemplary Embodiment

Explanation follows regarding a laser processing device according to anexemplary embodiment, with reference to FIG. 5. The present exemplaryembodiment is an embodiment in which the optical system of the exemplaryembodiment above has been changed. FIG. 5A illustrates a laserprocessing device 70 according to the present exemplary embodiment. FIG.5B illustrates a laser processing device 90, which is a modified exampleof the laser processing device 70.

As illustrated as an example in FIG. 5A, the laser processing device 70includes a laser source 74, a laser source 76, and an optical system 72.The wavelength of the laser source 74 is λ1, and the wavelength of thelaser source 76 is λ2 (≠λ1). Laser light of the laser source 74 andlaser light of the laser source 76 are both linearly polarized andpolarized wave directions are orthogonal to each other.

The optical system 72 according to the present exemplary embodimentincludes a polarizing prism 78, a ¼ waveplate 80, and lenses 82, 84, and86. The polarizing prism 78 is an optical element that multiplexes twolinearly polarized light beams having orthogonal wave polarizationdirections. The polarizing prism 78 multiplexes the laser light (lightbeam L1) from the laser source 74 with the laser light (light beam L2)from the laser source 76 and transmits the multiplexed laser lighttoward the ¼ waveplate 80. The ¼ waveplate 80 is an element thatconverts incident linearly polarized light into circularly polarizedlight. The ¼ waveplate 80 converts, into circularly polarized light, thelaser light from the laser source 74 and the laser light from the lasersource 76 that have been multiplexed by the polarizing prism 78, andforms the superimposition spot S at the processing point P of theworkpiece W.

In particular, the laser processing device according to the presentexemplary embodiment has an advantageous effect of enabling heterodyneinterference to be stabilized by using a ¼ waveplate when employing theabove described heterodyne interference between mutually orthogonallylinearly polarized light beams respectively having a wavelength λ1 and awavelength λ2, which are similar wavelengths. Further, the laserprocessing device according to the present exemplary embodiment enablesdependency on polarization of the processing light to be reduced when,for example, cutting metal, since the laser light at the processingpoint P is circularly polarized light.

As illustrated as an example in FIG. 5B, the laser processing device 90includes a laser source 93, a laser source 94, and an optical system 92.The wavelength of the laser source 93 is λ1, and the wavelength of thelaser source 94 is λ2. The polarization state of the laser light of eachlaser source is one of circular polarization.

The optical system 92 according to the present exemplary embodiment isconfigured including a dichroic mirror 95 and lenses 96, 97, and 98. Thedichroic minor 95 is an optical element that multiplexes two laser lightbeams having different wavelengths by reflecting one light beam andpassing the other light beam. As illustrated as an example in FIG. 5B,multiplexing is performed by reflecting the light beam L1 from the lasersource 93 and passing the light beam L2 from the laser source 94. Themultiplexed light beam L1 and the light beam L2 are focused by the lens98 and the superimposition spot S is formed at the processing point P ofthe workpiece W.

The laser processing device according to the present exemplaryembodiment has an advantageous effect of enabling the optical system tobe simplified since employing a dichroic mirror according to the presentexemplary embodiment eliminates the need to employ a ¼ waveplate,particularly when applying, as the wavelength λ1 and the wavelength λ2,a combination of wavelengths having frequencies separated by apredetermined wavelength (for example, a combination of an infraredregion wavelength and a visible wavelength in a 1 μm band). Further, thelaser processing device according to the present exemplary embodiment isable to achieve a less expensive laser processing device, since adichroic mirror is less expensive than a polarizing prism and there isno need to employ a ¼ waveplate.

Fifth Exemplary Embodiment

Explanation follows regarding a 3D printer (a three-dimensional shapingdevice) according to an exemplary embodiment that employs a laserprocessing device according to an exemplary embodiment above, withreference to FIG. 6A and FIG. 6B. The 3D printer is apparatus thatshapes solid objects (three-dimensional objects) based on 3D CAD data or3D CG data. The 3D printer employs, for example, a laminated shapingmethod as the shaping method. Minute focus diameter laser spots, namely,melted spots, are requested for the 3D printer to form a laminatedobject in some cases. The laser processing device according to theexemplary embodiments above is also suitable for achieving small meltedspots such as those needed in the 3D printer.

Namely, in the laser processing device according to the presentexemplary embodiment, laminated object production can be achieved withsmall melted spots by the CPU 302 independently controlling a region ofstrongest absorption and melting due to the superimposition region OA ofthe superimposition spot S, and a region that adjusts the amount of heatintroduced to the entire object by the no-superimposition region NA, atthe processing point P of the workpiece W.

As illustrated as an example in FIG. 6A, the 3D printer according to thepresent exemplary embodiment includes a processing light generator 100and a metal powder supplying mechanism 200. The processing lightgenerator 100 is a section having a similar function to the laserprocessing device described above. The processing light generator 100includes a laser source 102 that outputs laser light beams having pluralwavelengths (a case of two wavelengths is illustrated in the exampleillustrated in FIG. 6A) and a lens 104.

A light beam L1 having a wavelength λ1 and a light beam L2 having awavelength λ2 output from the laser source 102 are focused by the lens104 and the superimposition spot S is formed at the processing point Pfor forming the laminated shape.

The metal powder supplying mechanism 200 is configured including anozzle 202; a metal powder source and a conveyance section therefor,which are omitted from the drawings; a conveyance gas and a conveyancesection therefor; and a shielding gas and a conveyance section therefor.Note that the powder is not limited to a metal; a ceramic, a resin, orthe like may be employed.

As illustrated as an example in FIG. 6A, the nozzle 202 includes a metalpowder/conveyance gas channel 204 for supplying the metal powder servingas a laminating material (a material for performing lamination) togetherwith a conveyance gas (for example, nitrogen gas) as a powder-mixed gasPG, and a shielding gas channel 206 for supplying a shielding gas SG(for example, nitrogen gas) for shielding the processing point P fromthe exterior during lamination. As illustrated as an example in FIG. 6B,the nozzle 202 is configured such that the metal powder/conveyance gaschannel 204 and the shielding gas channel 206 are disposed in aconcentric circle arrangement as viewed from the leading end of thenozzle 202. Then, in the processing light generator 100, laminating isperformed by ejecting metal powder from the nozzle 202 while the lightbeams L1 and L2 are emitted on the processing point. When doing so, theprocessing point P where laminating is being performed is shielded bythe shielding gas SG and an atmosphere of the conveyance gas ismaintained around the processing point P.

In cases in which laminating is performed, as illustrated as an examplein FIG. 6A the powder-mixed gas PG is discharged from the nozzle 202 andthe light beams L1 and L2 from the laser source 102 are emitted onto themetal powder included in the powder-mixed gas PG. The energy of the spotS is received at the processing point P, the heated metal powder melts,and a laminated portion of solidified metal is formed.

Note that in the exemplary embodiments above, although explanation hasbeen given regarding examples of modes in which there are plural lasersources having different wavelengths in the laser processing device,there is no limitation thereto. The wavelengths of the plural lasersources may be the same wavelength. Although heterodyne interferencedoes not occur in such cases, after the processing point has been meltedby the superimposition region OA having a predetermined energy density,the CPU 302 controls the processing characteristics by causing theenergy of the no-superimposition region NA, which has a lower energydensity than the superimposition region OA, to be absorbed, therebyemploying the superimposition spot S to achieve an advantageous effect,namely, an advantageous effect of improved energy efficiency.

In each of the exemplary embodiments above, although explanation hasbeen given regarding examples of modes in which the superimposition spotS is formed using plural laser sources, there is no limitation thereto.For example, a mode may be configured such that laser light from asingle laser source is split to form the superimposition spot S. In suchcases, configuration may be made such that, for example, laser lightfrom a single laser source is split into plural laser light beams by abeam splitter or the like and the split plural laser light beams havethe characteristics described above (energy density, encompassingrelationship, and the like) so as to form the superimposition spot S.According to such a configuration, since the number of laser sources canbe reduced, the advantageous effects of the superimposition spot Saccording to technology disclosed herein can be achieved using a laserprocessing device having a simpler configuration.

Note that in the exemplary embodiments above, although examples havebeen given of cases in which the program 308 is read from the secondarystorage section 306, the program 308 does not necessarily need to bepre-stored on the secondary storage section 306. For example, asillustrated in FIG. 8, the program 308 may be first stored on anarbitrarily selected portable storage medium 400, such as an SSD, USBmemory, or a CD-ROM. In such cases, the program 308 of the storagemedium 400 is installed to the laser processing device 10 (30, 50, 70,90), and the installed program 308 is executed by the CPU 302.

Further, the program 308 may be stored in a storage section such asanother computer or a server device connected to the laser processingdevice 10 (30, 50, 70, 90) through a communication network (notillustrated in the drawings), and the program 308 may be downloaded bythe laser processing device 10 (30, 50, 70, 90) when needed. In suchcases, the downloaded program 308 is executed by the CPU 302.

Further, in the exemplary embodiments above, although examples have beengiven regarding cases in which a controller according to technologydisclosed herein is implemented by a software configuration that employsa computer, technology disclosed herein is not limited thereto. Forexample, instead of a software configuration that employs a computer,the controller according to technology disclosed herein may beimplemented using a hardware configuration alone, such as afield-programmable gate array (FPGA) or an application specificintegrated circuit (ASIC). Further, the controller according totechnology disclosed herein may be implemented by a combination ofsoftware configuration and hardware configuration.

Obviously, various modifications may be implemented within a range notdeparting from the spirit of the present invention.

The disclosure of Japanese Patent Application No. 2016-056211, filedMar. 18, 2016, is incorporated herein by reference in its entirety.

All publications, patent applications, and technical standards mentionedin this present specification are herein incorporated by reference tothe same extent as if each individual publication, patent application,or technical standard was specifically and individually indicated to beincorporated by reference.

REFERENCE SIGNS LIST

-   -   10 laser processing device    -   12 optical system    -   14, 16 laser source    -   18, 20, 22, 24 lens    -   30 laser processing device    -   32 optical system    -   34, 36 laser source    -   38, 40, 42 lens    -   50 laser processing device    -   52 optical system    -   54, 56 minor    -   58 lens    -   70 laser processing device    -   72 optical system    -   74, 76 laser source    -   78 polarizing prism    -   80 ¼ waveplate    -   82, 84, 86 lens    -   90 laser processing device    -   92 optical system    -   93, 94 laser source    -   95 dichroic minor    -   96, 97, 98 lens    -   100 processing light generator    -   102 laser source    -   104 lens    -   200 metal powder supplying mechanism    -   202 nozzle    -   204 metal powder/conveyance gas channel    -   206 shielding gas channel    -   Car carrier component    -   Env envelope component    -   L1, L1 light beam    -   PG powder-mixed gas    -   SG shielding gas    -   P processing point    -   R1, R2 focus diameter    -   S superimposition spot    -   S1 to S5 spot    -   OA superimposition region    -   NA no-superimposition region    -   W workpiece

1. A laser processing device comprising: a plurality of laser sources;and a focusing section that focuses respective light beams of theplurality of laser sources to form a plurality of focus points on aworkpiece, such that respective portions of at least some of theplurality of focus points are overlapping, wherein: the plurality oflaser sources have mutually different wavelengths, and the laserprocessing device further comprises a controller that: when performinglaser processing, after melting the workpiece at a region where aplurality of the focus points are overlapped, controls an input heatprofile at a region within each of the plurality of the focus pointswhere the plurality of focus points do not overlap, and controlsabsorption characteristics of the workpiece with a carrier component ofa superimposition beam generated by superimposing light beams from eachof the plurality of the laser sources, wherein wavelengths of the eachof the plurality of the laser sources are selected in order to raise theabsorption characteristics. 2-4. (canceled)
 5. The laser processingdevice of claim 1, wherein: respective lights of the plurality of lasersources have different wavelengths, sizes of the plurality of focuspoints differ from one another, and one of the focus points internallyencompasses another of the focus points.
 6. (canceled)
 7. The laserprocessing device of claim 1, wherein the focusing section includes anoptical system that focuses each of the respective light beams.
 8. Athree-dimensional shaping device comprising: a laminating sectionincluding a material supply section that supplies a material forperforming lamination to form a laminated object; and the laserprocessing device of claim 1, wherein the laminating section performslamination by: supplying the material onto the laminated object from thematerial supply section while moving the laminated object relative tothe material supply section and the light beams, and emitting the lightbeams onto the supplied material.
 9. A laser processing method performedby a laser processing device that includes a plurality of laser sourcesand a focusing section that focuses respective light beams of theplurality of laser sources to form a plurality of focus points on aworkpiece, the laser processing method comprising: focusing using thefocusing section such that respective portions of at least some of theplurality of focus points are overlapping, wherein: the plurality oflaser sources have mutually different wavelengths; and the laserprocessing method further comprises: melting the workpiece in a regionwhere the plurality of the focus points are overlapped, controlling aninput heat profile at a region within each of the plurality of the focuspoints where the plurality of focus points are not overlapped, andcontrolling absorption characteristics of the workpiece with a carriercomponent of a superimposition beam generated by superimposing lightbeams from each of the plurality of the laser sources, whereinwavelengths of the each of the plurality of the laser sources areselected in order to raise the absorption characteristics. 10.(canceled)